Non-equilibrium dynamics of interacting Fermi systems in quench experiments

TL;DR

This paper investigates the non-equilibrium dynamics of ultracold Fermi gases after a rapid quench, focusing on collective mode growth, ferromagnetic textures, and pairing instabilities.

Contribution

It provides a detailed analysis of the short-time dynamics and unstable mode growth in quenched Fermi systems near Feshbach resonances, highlighting new insights into ferromagnetic and pairing instabilities.

Findings

Growth rates of unstable modes are quantified.

Predicted lengthscales of ferromagnetic and pairing textures.

Distinct dynamics on repulsive and attractive sides of the resonance.

Abstract

We describe the dynamics of two component non-interacting ultracold Fermions which are initially in thermal equilibrium and undergo a rapid quench to either the repulsive or attractive side of a Feshbach resonance. The short time dynamics is dominated by the exponentially growing collective modes. We study the Stoner instability and formation of ferromagnetic textures on the repulsive side, and the pairing instability towards BCS or FFLO-like states (determined by the population imbalance) on the attractive side. In each case, we evaluate the growth rate of unstable modes and predict the typical lengthscale of textures to be formed.